With the gradually improved requirements of users on indoor environments of buildings, air conditioners are more and more popular, and the energy consumption of the air conditioners is also increasing day by day. Among the entire energy consumption of buildings, the energy consumption of air-conditioning systems usually occupies 40%-50%.
Taking a building which employs an central air conditioning system for example, the major equipment of the central air conditioning unit include chiller, chilled water pump and condenser water pump, wherein the operating process thereof is as follows: the chiller prepares chilled water with certain temperature and chilled water pump conveys the chilled water to the end-users (for example, air-conditioned rooms) to exchange heat with indoor air, so as to satisfy the temperature and humidity requirements of the indoor environment; the temperature of the chilled water after heat exchanging with the indoor air is raised, and then chilled water is return to chiller and being cooled by chiller, this is a closed cycling process; the heat (mainly including the indoor heat absorbed by the chilled water and the heat generated by the self loss of the chiller during working) is ejected by the recycled cooling water, conveyed by condenser water pump) to cooling tower or other heat exchanger device, and finally dissipated into the atmosphere environment. The annual power consumption of the central air conditioning system contributes more than 30% of the annual power consumption of the entire building.
The air-conditioning system design cooling load is usually calculated according to the extreme climate condition of the location of the building, and then determining the capacity of the air conditioning system. However, the situation of the maximum cooling load condition appears in very short periods in each year actually. Therefore, the central air-conditioning system operates under a condition far smaller than the nominal capacity thereof in most of the time. In this manner, how to operate the air conditioning system according to the actual cooling load becomes a critical issue. While in the related research, some methods may be feasible under stable lab conditions. But in actual operating process, since all the devices of the air conditioning system are under a continuous operating status, the cooling load and weather parameters change anytime, and the energy consumption is difficult to be optimized using the present control methods, and a contrary effect may even be produced possibly. Therefore, how to reduce the energy consumption of the air conditioning system with a flexible and robust control method is critical to reduce the entire energy consumption of the building.